The present invention relates to a binding metal with a heat-shrinkable sheet, the production method thereof, and a covering method with a heat-shrinkable sheet.
To maintain the insulating property, the corrosion resistance, the water resistance of an object to be covered, such as a metal pipe, a cable, etc., covering the object to be covered with a heat-shrinkable sheet and shrinking the sheet by heating has been thus far widely carried out. In this case, to hold the heat-shrinkable sheet, the following techniques are proposed.
(1) Japanese Utility Model Laid-Open No. 169527/1982: The invention is a technique of covering an object with a heat-shrinkable sheet, and heat-shrinking the same in a state that end portions of the heat-shrinkable sheet are held between a pair of rod-form members and also are fixed by holding the rod-form members by a clip.
(2) Japanese Patent Publication No. 48860/1989: The invention is also a technique of covering an object with a heat-shrinkable sheet and holding the end portions of the heat-shrinkable sheet by a pair of rod-form members. In this case, both end portions of the heat-shrinkable sheet facing each other by binding both end portions with a wire together with the object to be covered are pushed to the side of the object. Furthermore, the heat-shrinkable sheet is held by clamping the rod-form members by a clip, and the heat-shrinkable sheet is heat-shrunk in this state.
However, a clip is required to obtain a clamping force in each of the above-described techniques, because the rod-form members have a straight-line form. Therefore, the number of parts is increased, whereby the workability at fixing the heat-shrinkable sheet is poor. Particularly, in the above-described technique (2) of the prior art, binding with a wire is necessary, which makes the work complicated.
Also, because a clip has a large heat capacity, it becomes a hindrance for heating and cooling. That is, there are problems in which at heating, the clip shields the hot blast of the heating torch lamp and also after heating, requires a period of cooling of the clip.
Also, because the wire binding in the above-described technique (2), winds the rod-form members together with the object to be covered, when the object is a polyethylene-covered pipe, etc., the polyethylene cover is softened by the heat at heating the heat-shrinkable sheet whereby it is a possible that the wire may enter the softened cover.
Furthermore, in each of the above-described techniques, when there exist irregular portions on the surface of an object to be covered, it is difficult to shrink a heat-shrinkable sheet along the object and a gap is formed between the object and the heat-shrinkable sheet.
Accordingly, the main object of the invention is to provide a. binding metal for covering an object with a heat-shrinkable sheet, which can cover even an object having irregular portions on the surface thereof with a heat-shrinkable sheet without forming gaps and further carry out the operation with good workability, a production method of the binding metal, and a covering method with a heat-shrinkable sheet.
The binding metal of the invention is a binding metal for covering an object with a heat-shrinkable sheet and holding them in a state that both end portions of, the sheet face each other, and has two long members holding the heat-shrinkable sheet between them. These long members have an opening and closing portion at one end portion such that when the long members are substantially parallel, the distance between the long members at the opening and closing portion is wider than that at the intermediate portion. That is, at least one end portion of the long members is formed apart from each other. Also, a clamping force is applied to the heat-shrinkable sheet by closing the opening and closing portion.
A rod-form material or a belt-form material is suitable as the material constituting the binding metal. As the material constituting the binding metal, a metal having a proper rigidity is preferred. For example, a wire can be utilized.
Also, as a practical embodiment of xe2x80x9cwhen the long members are substantially parallel, the distance between the long members at the opening and closing portion is wider than that at the intermediate portion xe2x80x9d, there is a case that one end portion of each of long member is bent at an angle and a case that both end portions are bent at an angle. Furthermore, the long members may be formed in circular arc.
In the binding metal, a heat-shrinkable sheet is inserted between the long members in the state that at least the end portions thereof are apart from each other, and holds both end portions of the long members, then the heat-shrinkable sheet is clamped. This case requires holding both end portions of the long members when the two long members are independent and sometimes the process of inserting the heat-shrinkable sheet is difficult. Thus, one end of the long members may be connected. That is, the binding member has the form of folding from one long member to the other long member via the connected portion.
The binding metal is, as a matter of course, used for an object to be covered having no irregular portion, for example, a rod-form material having a diameter in the lengthwise direction, but can be effectively utilized for an object to be covered having irregular portion(s) on the surface thereof. That is, when an object to be covered has an irregular portion, it is desirable to form a deformed portion formed almost fitting the irregular portion of the object to the long members, which extends to the opening and closing portion. At least a part of the deformed portion is projected from the face of the opening and closing portion making the opening or closing action.
By holding the binding metal of both end portions of a heat-shrinkable sheet, from the initiation of heating to the completion of heating, the heat-shrinkable sheet can be held in the form almost fitting the irregular portion of the object, and the formation of a gap between the heat-shrinkable sheet and the object to be covered can be restrained.
To hold the opening and closing portions in a closed state, a hooking portion is formed on an end portion of at least one long members in the opening and closing portions, and by engaging the end portion of the other member in the opening and closing portion, the portion may be maintained in the closed state. For example, there is a construction that the end portion of one of the long members is bent in a U-form and the end portion of the other long member is hooked by the U-formed portion. In other embodiment, a ring may be put over the peripheries of the long members.
Also, the production method of the binding metal for applying a heat-shrinkable sheet of the invention relates to a method of producing a binding metal using a long member of a circular arc, and includes a step of forming a long member in a circular arc and a step of folding the long member formed in a circular arc at about the center thereof such that both end portions of the long member are apart from each other. According to the production method, a binding metal can be produced in less process steps as compared with the case of bending long members.
On the other hand, the covering method of the invention is a method of covering an object having a small diameter portion and a large diameter portion with a heat-shrinkable sheet, which includes:
(1) a step of placing an adhesive in the heat-shrinkable sheet at a position corresponding to the small diameter portion;
(2) a step covering an object with the heat-shrinkable sheet with adhesive in contact with at least part of the small diameter portion;
(3) a step of holding the heat-shrinkable sheet with the above described binding metal in a state in which both end portions of the heat-shrinkable sheet are facing each other; and
(4) a step of shrinking the heat-shrinkable sheet by heating.
By the covering method of the invention, even an object to be covered having a small diameter portion and a large diameter portion can be securely covered by the heat-shrinkable sheet without forming gaps between the small diameter portion and the heat-shrinkable sheet. Particularly, it is desirable that by placing an adhesive, the portion between the small diameter portion and the large diameter portion is formed in a tapered form as gentle as possible. In addition, xe2x80x9cby placing an adhesive xe2x80x9d includes the case of attaching an adhesive sheet (tape) in addition to the case of coating an adhesive.